A hoist assembly for lifting a load or equipment into and out of a vehicle, such as a pickup truck, often is required since the load may not be lifted easily by hand. Rather than having separate hoist assemblies to load a vehicle and to unload the vehicle at its destination or at multiple destinations, it is convenient to have a hoist assembly which may be mounted to the vehicle and which may travel with the vehicle.
Various hoist or crane assemblies for use with a vehicle have been provided in the prior art. U.S. Pat. No. 4,419,038 to Pendergraft, issued Dec. 6, 1983, provides a hoist assembly which is integrated into a vehicle bumper. The assembly folds into the bumper and thus may be stored when not in use. However, the device of Pendergraft requires adaptation of the bumper and the vehicle itself in order to implement the hoist. U.S. Pat. No. 5,439,343 to Watson, issued Aug. 8, 1995, also provides a combined bumper and hoist assembly. U.S. Pat. No. 6,499,610 to Spitsbergen, issued Dec. 31, 2002, provides a compact hoist assembly which may be mounted via a base plate onto the cargo space of a vehicle, the flat bed of a truck or the roof of a building. U.S. Pat. No. 6,821,075 to van der Horn, issued Nov. 23, 2004, discloses a hoist adapted to fit with a standard vehicle receiver hitch with two structural supports extending from a boom support. While van der Horn notes the legs may be adjusted to account for use of a vehicle and the hitch assembly on uneven terrain, van der Horn does not provide a convenient and accurate means for positioning the hitch hoist. The support legs in the assembly disclosed by van der Horn may be adjusted but this would impact the leveling of the device both in the horizontal and vertical planes, making it difficult to provide a device which is both level and upright.
Other devices also have been provided such as the HITCHHOIST™ product by Grablock Inc. This also provides a hoist assembly mounted to a vehicle hitch, however, leveling of the hoist assembly is provided in a single direction only. As well, the lift capacity of the hoist is limited by the rated tongue weight of the vehicle hitch.
Leveling of the hoist assembly in the horizontal plane and adjustment of the hoist assembly to a vertical position is desirable to ensure proper operation of the device, especially under heavy loads. Further, as a load is lifted using a hoist apparatus attached to a vehicle as described above, the back end of the vehicle may sink under the weight of the load, causing the hoist to become unleveled. An improperly leveled assembly may result in uneven distribution of the load, causing the load to swing or for the hoist to shift or topple, creating a safety concern. Improper leveling also can cause increased strain on the assembly and metal fatigue or failure. As well, it is desirable not to exceed the lift capacity of the hoist assembly as exceeding the maximum load capacity raises safety concerns and also may cause the load to swing or for the hoist to shift or topple.
Thus, it would be desirable to provide a hoist assembly which provides for lifting of various loads without modification to the vehicle itself or additional supports or devices to increase the lift capability of the vehicle. Further, it would be desirable to provide a hoist assembly that may be readily leveled horizontally and adjusted to a vertical position, and which indicates if the load capacity has been exceeded, in order to ensure safe and proper lifting of the load.